Baby Sleep: Understanding Your Newborn’s Sleep Biology

One of the most talked-about topics for new parents is baby sleep. It can feel like a mystery—but understanding the biology behind baby sleep can empower you to navigate it with confidence.

Professor Helen Ball, a leading sleep scientist, shares four key truths that every new parent should know about how babies sleep. At Having a Baby Classes, we aim to provide evidence-based, practical information to support your parenting journey.

1. Babies Know How to Sleep: It’s an Innate Biological Process

Babies don’t need to be taught how to sleep—they already know how. From the womb, sleep is a natural part of their development. Like breathing or feeding, sleep is instinctual, not a learned skill.

Instead of trying to train your baby to sleep, focus on creating a supportive sleep environment and responding to their cues. Understanding this can reduce stress and shift your mindset from control to connection.

2. The Myth of Dark Rooms: Helping Develop Day-Night Rhythms

Contrary to popular advice, putting your baby in a dark room during the day doesn’t help them sleep better—at least not in the early weeks. Newborns are born without a circadian rhythm, so they don’t yet understand the difference between night and day.

Expose Babies to Natural Light and Everyday Sounds

Babies start developing their internal clock between 3–4 months of age. Until then, keeping your baby around natural daylight and household sounds helps their body begin to recognise day vs. night.

Keep Babies Close During Day Sleeps

Letting your baby nap near you during the day supports both their safety and their developing circadian rhythm. It also allows you to monitor them more easily and provides them with a sense of security.

3. Sleep Pressure, Not Schedules: Sleep When Tired

Many parents try to stick to strict nap schedules, but babies can’t sleep on command. They need enough sleep pressure—the biological drive to sleep after being awake—to fall asleep naturally.

What is Sleep Pressure?

Sleep pressure builds as babies stay awake and use mental energy. When the pressure peaks, your baby will naturally want to sleep. Forcing a nap too early often leads to tears—for both baby and parent.

Follow Baby’s Sleep Cues

Watch for signs like yawning, fussiness, or eye rubbing. Being flexible and responsive to these cues is more effective than sticking to rigid nap times.

4. In Your Arms: The Safest, Most Comforting Place

While a bassinet might be the ideal in your mind, the truth is: most babies sleep best in your arms or on your body. This isn’t a bad habit—it’s biology.

Babies Are Wired for Closeness

They crave warmth, your heartbeat, your scent, and the sound of your voice. This need for closeness is rooted in survival instincts. It’s not spoiling—it’s comforting.

While your baby doesn’t have to sleep on you all the time, recognising this biological need helps you approach those clingy moments with more empathy.

Always follow safe sleep practices, especially when holding your baby while resting or considering co-sleeping arrangements.

Embrace Your Baby’s Unique Sleep Journey

Understanding your newborn’s sleep biology—thanks to insights from Professor Helen Ball—can help you stop fighting nature and start working with it. Babies:

• Are born knowing how to sleep
• Develop day-night rhythms over time
• Sleep best when they’re truly tired
• Often find the most comfort sleeping near you

At Having a Baby Classes, we’re here to help you feel empowered and informed. A responsive, flexible approach to sleep can make the early months more peaceful for your whole family.